1. Field of the Invention
The present invention relates generally to a sensor for detecting a user's physiologic information, and in particular, to a compact sensor for measuring the physiologic data, such as a pulse rate.
2. Description of the Related Art
The pulse rate is a numerical value based on which the stress, the state of exercise, the quantity of exercise, etc. can be measured. Conventionally, an electrocardiogram (ECG) sensor has been deployed to measure the pulse rate by detecting ECG signals using multipolar electrodes. In addition, a photosensor, by irradiating a light on a skin surface of a living body using a light emitting diode (LED), detects a light output from the skin surface within the living body using a photodiode (PD).
Recently, intensive research efforts are being concentrated on small devices equipped with a sensor for measuring a user's physical information. However, since the above-stated ECG sensor and photosensor require a dedicated space for their installation, they can be hardly applied to the small devices.
Therefore, there is a need a compact sensor for measuring living body information that can be readily incorporated and utilized in small devices such as an earphone.